Proteins often carry out their functions by working as assemblies of multiple proteins, with or without other biomolecules or ligands bound. Characterization of protein complexes/assemblies, including identification of all binding partners, their relative architecture/topology in the complex, conformational changes upon binding and the relative binding affinities of partners is key to developing a better understanding of how these complex systems carry out their normal biological functions and how alterations of architecture can lead to malfunction. MS is emerging as a powerful tool for structural biology, with the combination of multiple MS approaches enabling the structural characterization of biomacromolecules. However, development of both MS instrumentation and methods is necessary to fully implement the use of MS in routine, reliable, and rapid structural characterization studies. To advance the technological development of native MS for structural biology applications and to illustrate how native MS can guide and integrate with other structural biology approaches, we have identified three main classes of protein complexes for which significant technological challenges exist, compelling PIs to use multiple structural biology approaches. These are 1) protein:protein, 2) membrane protein and membrane protein:lipid complexes, and 3) RNA:protein, complexes. The DBPs were selected to encompass projects with high biomedical significance where progress depends on solving substantial technical challenges. These projects will benefit significantly from improved native MS workflows. Solving their structural challenges, in the context of other structural tools that they use, will also provide solutions and guidance that are applicable to a much broader spectrum of researchers. Effective communication is key to the progress of the DBPs, so that the Resource fully understands the nature of the biological problem being addressed and so that the collaborating investigators fully understand the current capabilities of each of the technologies. Initial project meetings have been held for each of the DBPs and preliminary data have been obtained. Regular meetings will be held to assess the progress and plan future experiments. DBP investigators and their groups will be encouraged to present the work at conferences they attend, with an appropriate acknowledgement of the nMS?SB Resource. A DBP will be considered successfully completed when it has reached a point where multiple high-quality manuscripts are prepared and published, the DBP?s questions can be answered with technology existing at that stage, and the DBP is no longer driving the Resource to improve the native MS technology. The Resource will be involved with the authoring and preparation of each of the relevant joint manuscripts. For publication, journals will be targeted that have high-impact and are read by the broad community, which aids in our dissemination plan of bringing the technology to a broad audience, including structural biologists and biomedical researchers.